NPE when using simple generic class

[TWiStErRob]

The following classes make JFixture throw an NPE (similar to #29, but not inner class):

class SomeClass {
    final Wrapper<String> wrapper;

    public SomeClass(Wrapper<String> data) {
        this.wrapper = data;
    }
}

class Wrapper<T> {
    final T data;

    public Wrapper(T data) {
        this.data = data;
    }
}

java.lang.NullPointerException
    at com.flextrade.jfixture.utility.SpecimenType.<init>(SpecimenType.java:37)
    at com.flextrade.jfixture.utility.SpecimenType.<init>(SpecimenType.java:12)
    at com.flextrade.jfixture.utility.SpecimenType$3.<init>(SpecimenType.java:55)
    at com.flextrade.jfixture.utility.SpecimenType.withGenericContext(SpecimenType.java:55)
    at com.flextrade.jfixture.utility.ParameterUtils.convertPossibleGenericTypeToSpecimenType(ParameterUtils.java:50)
    at com.flextrade.jfixture.utility.ParameterUtils.getParameterTypes(ParameterUtils.java:43)
    at com.flextrade.jfixture.utility.ParameterUtils.getConstructorArguments(ParameterUtils.java:15)
    at com.flextrade.jfixture.builders.GenericConstructorRelay.create(GenericConstructorRelay.java:27)
    at com.flextrade.jfixture.builders.CompositeBuilder.create(CompositeBuilder.java:26)
    at com.flextrade.jfixture.behaviours.autoproperty.AutoPropertyBuilder.create(AutoPropertyBuilder.java:22)
    at com.flextrade.jfixture.behaviours.recursion.RecursionGuard.create(RecursionGuard.java:33)
    at com.flextrade.jfixture.behaviours.noresolution.NoResolutionGuard.create(NoResolutionGuard.java:27)
    at com.flextrade.jfixture.behaviours.specimentype.SpecimenTypeInjector.create(SpecimenTypeInjector.java:26)
    at com.flextrade.jfixture.SpecimenBuilderContext.resolve(SpecimenBuilderContext.java:13)
    at com.flextrade.jfixture.builders.ClassToConstructorRelay.create(ClassToConstructorRelay.java:51)
    at com.flextrade.jfixture.builders.CompositeBuilder.create(CompositeBuilder.java:26)
    at com.flextrade.jfixture.behaviours.autoproperty.AutoPropertyBuilder.create(AutoPropertyBuilder.java:22)
    at com.flextrade.jfixture.behaviours.recursion.RecursionGuard.create(RecursionGuard.java:33)
    at com.flextrade.jfixture.behaviours.noresolution.NoResolutionGuard.create(NoResolutionGuard.java:27)
    at com.flextrade.jfixture.behaviours.specimentype.SpecimenTypeInjector.create(SpecimenTypeInjector.java:26)
    at com.flextrade.jfixture.SpecimenBuilderContext.resolve(SpecimenBuilderContext.java:13)
    at com.flextrade.jfixture.utility.ParameterUtils.convertTypesToInstances(ParameterUtils.java:28)
    at com.flextrade.jfixture.utility.ParameterUtils.getConstructorArguments(ParameterUtils.java:16)
    at com.flextrade.jfixture.builders.GenericConstructorRelay.create(GenericConstructorRelay.java:27)
    at com.flextrade.jfixture.builders.CompositeBuilder.create(CompositeBuilder.java:26)
    at com.flextrade.jfixture.behaviours.autoproperty.AutoPropertyBuilder.create(AutoPropertyBuilder.java:22)
    at com.flextrade.jfixture.behaviours.recursion.RecursionGuard.create(RecursionGuard.java:33)
    at com.flextrade.jfixture.behaviours.noresolution.NoResolutionGuard.create(NoResolutionGuard.java:27)
    at com.flextrade.jfixture.behaviours.specimentype.SpecimenTypeInjector.create(SpecimenTypeInjector.java:26)
    at com.flextrade.jfixture.SpecimenBuilderContext.resolve(SpecimenBuilderContext.java:13)
    at com.flextrade.jfixture.builders.ClassToConstructorRelay.create(ClassToConstructorRelay.java:51)
    at com.flextrade.jfixture.builders.CompositeBuilder.create(CompositeBuilder.java:26)
    at com.flextrade.jfixture.behaviours.autoproperty.AutoPropertyBuilder.create(AutoPropertyBuilder.java:22)
    at com.flextrade.jfixture.behaviours.recursion.RecursionGuard.create(RecursionGuard.java:33)
    at com.flextrade.jfixture.behaviours.noresolution.NoResolutionGuard.create(NoResolutionGuard.java:27)
    at com.flextrade.jfixture.behaviours.specimentype.SpecimenTypeInjector.create(SpecimenTypeInjector.java:26)
    at com.flextrade.jfixture.JFixture.create(JFixture.java:82)
    at com.flextrade.jfixture.JFixture.create(JFixture.java:78)
    at SomeClassJFixtureTest.test(SomeClassJFixtureTest.java:13)

Here's the test to drive it:

import com.flextrade.jfixture.JFixture;

import org.junit.Test;

import static org.junit.Assert.assertNotNull;

public class SomeClassJFixtureTest {

    @Test
    public void test() {
        SomeClass fixt = new JFixture().create(SomeClass.class);
        assertNotNull(fixt);
        assertNotNull(fixt.wrapper);
        assertNotNull(fixt.wrapper.data);
    }
}

[TWiStErRob]

@philipwhiuk do you have any idea what's wrong here? It looks like a normal use case.